This slide show sheds some light on a few definitions from the geographical vocabulary

1. Population Distribution
Population distribution is the pattern of where people live, it is the
arrangement of the population on a certain area according with conditions
and requirements of the society (eg race, age, sex, income)
http://www.geography.learnontheinternet.co.uk/topics/popn1.html

2. Human Settlement Pattern
The science of human settlements, including city or
community planning and design.
http://www.thefreedictionary.com/Human+settlement+patterns

3. Clustered Settlement
A clustered settlement is a pattern of settlement in which the
houses and building and living needs are laid out closely
together.
http://wiki.answers.com/Q/What_is_the_pattern_of_settlement_for_E

4. Scattered Settlement
In a scattered settlement, dwellings and other buildings are
spaced over an extensive area. They are usually found in
hilly tracks, thick forests and regions of extreme climate.
Http:/wikianswers.com/Q/what is a scattered
settlement#slide=3

5. Linear Settlement
A linear settlement, is a (normally small to medium-sized)
settlement or group of buildings that is formed in a long line.
Many follow a transport route, such as a road, river, or canal,
though some form due to physical restrictions, such as
coastlines, mountains, hills or valleys
http://en.wikipedia.org/wiki/Linear_settlement

6. Population Density
Population density is a measurement of population per unit
area or unit volume. It is usually applied to the settlement of
living organisms, most frequently humans.
http://en.wikipedia.org/wiki/Population_density

7. Overpopulation
Overpopulation occurs when a population of a species
exceeds the carrying limit of their ecological surroundings
http://en.wikipedia.org/wiki/Overpopulation